1. Field of the Invention
The present invention relates to an optical signal processor and an optical assembly.
2. Description of the Related Art
Non Patent Document 1 (R. Krishnamurthy, The Luxtera CMOS Integrated Photonic Chip in a Molex Cable, [online], chipworks, 2012 Dec. 3, [searched Apr. 11, 2014], URL:http//www.chipworks.com/blog/technologyblog/2012 Dec. 3/the-luxtera-cmos-integrated-photonic-chip-in-a-molex-cable/) discloses a technology for mounting optical fibers on a complementary metal oxide semiconductor (CMOS) integrated photonic chip. The CMOS integrated photonic chip is a chip including a Si substrate on which complementary metal oxide semiconductor (CMOS) devices, which perform digital signal processing, and optical waveguides, which perform optical signal processing, are integrated. The CMOS integrated photonic chip according to Non Patent Document 1 includes polarization grating couplers (PGCs) from which polarized light is emitted. Each PGC has an optical fiber bonded to a surface thereof, and the polarized light emitted from the PGC is optically coupled to the core of the optical fiber.
Polarization maintaining fibers (PMFs) are used to transmit polarized light through optical fibers. A polarization maintaining fiber is an optical fiber having a stress imparting part therein. A stress applied to the core of the optical fiber causes birefringence in the core of the optical fiber. Due to the birefringence, the polarization maintaining fiber is capable of propagating the polarized light while maintaining the polarization of the polarized light.